The present invention relates to novel compositions having fertilising and anti-fungal effects, to processes for their preparation, and to methods of fertilising plants and controlling fungi using them.
Phosphorus is one of the essential major elements required by plants and it is usually supplied to plants in the form of phosphate and/or polyphosphate. Phosphates are the salts of phosphoric acid (having the formula H3PO4 and molecular weight of 98). In recent years, it has been shown that plants can obtain phosphorus from phosphonates (sometimes also referred to as phosphites) which are the salts (organic or inorganic) of phosphonic acid (also referred to as phosphorous acid) (having the formula H3PO3 and molecular weight of 82). See, for example, U.S. Pat. Nos. 5,514,200 and 5,830,255 to Lovatt; U.S. Pat. No. 5,707,418 to Hsu; U.S. Pat. No. 5,800,837 to Taylor. These describe formulations containing phosphorous acid or phosphonates suitable as fertilisers for plants. It has also been shown that phosphonate compounds are useful as fungicides, especially where the fungal organisms are phycomycetes or oomycetes. See, for example, U.S. Pat. Nos. 4,075,324 and 4,119,724 to Thizy; U.S. Pat. No. 4,139,616 to Lacroix et al; U.S. Pat. Nos. 4,698,334, 4.806,445 and 5,169,646 to Honriere et al; U.S. Pat. Nos 4,935,410 and 5,070,083 to Bartlet; U.S. Pat. No. 5,736,164 to Taylor. These describe formulations, containing phosphorous acid or phosphonates, suitable as fungicides for plants.
Ammonium thiosulphate and potassium thiosulphate, either alone or mixed with other liquid fertiliser components, have been used for many years as fertilisers. See literature on xe2x80x9cThio-sulxe2x80x9d(copyright) and KTS(copyright) sulphur fertilisers produced by Tessenderlo Kerley. See also UK Patent No. GB 2,259,912 to Sampson, which describes the use of ammonium thiosulphate in a plant growth stimulator.
WPI Abstract Accession No. 91-249421 discloses a cut flower preserving agent comprising a water-soluble silver salt (100 pts. wt.) and thiosulphate (300-2500 pts. wt.) to which a phosphite (30-300 pts. wt.) is added as a stabilising agent.
Some of the problems with the prior art are that the fertilising effect of phosphonate is less than might be expected from the amount of phosphorus applied, and the fungicidal effect is fairly limited in terms of the types of pathogen controlled. This is due to a complex mode of action involving a combination of some fungistatic action and natural plant defences coming into play (See Guest D I and Grant B R (1991)xe2x80x94The Complex action of phosphonates in plantsxe2x80x94Biological Reviews 66, 159-187). The use of phosphonate, whilst improving the resistance of plants to infections of downy mildew (eg Plasmopora) and Phytophthora diseases, does tend to increase the risk of ascomycete (eg Erysiphe) infections. The present invention seeks to provide a solution to these problems.
According to one aspect of the present invention there is provided a fertiliser composition comprising at least one phosphonate and at least one thiosulphate.
According to another aspect of the present invention there is provided a fertiliser composition comprising at least one phosphonate and at least one salicylic acid, homologue, derivative, or salt thereof.
According to yet another aspect of the present invention there is provided a fertiliser composition comprising at least one thiosulphate and at least one salicylic acid, homologue, derivative, or salt thereof.
According to a further aspect of the present invention there is provided a fertiliser composition comprising at least one thiosulphate, at least one phosphonate and at least one salicylic acid, homologue, derivative, or salt thereof.